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Analyzing distortion contributions in a complex device model

Timo Rahkonen (Department of Electrical Engineering, University of Oulu, Oulu, Finland)
Janne P. Aikio (Department of Electrical Engineering, University of Oulu, Oulu, Finland)



The purpose of this paper is to propose a method to reduce the non-linear distortion of a transistor to its input and output ports to aid distortion contribution analysis (DCA). This is especially needed when the internal structure of a device model is complex.


The non-linear distortion generated by all non-linear sources inside a device model are reduced to transistor i/o ports by LMSE fitting techniques. Simulations of an LDMOS power transistor are used to compare the reduced distortion results with the actual non-linear sources.


It is shown, that device models where the current sources are split by intermediate nodes cause superficial results, when distortion contributions are calculated as a superposition of contributions from individual non-linear sources. The proposed iterative fitting technique works.

Research limitations/implications

Some non-quasistatic effects and the transfer functions from external terminals to internal controlling nodes are not covered.

Practical implications

The analysis is a step toward a generic non-linear distortion contribution simulation tool that would aid the designers to develop more linear analog circuits.


The concept of DCA itself is fairly new. This paper makes a step to represent the distortion sources in a canonical way.



This research was funded by Academy of Finland.


Rahkonen, T. and P. Aikio, J. (2014), "Analyzing distortion contributions in a complex device model", COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Vol. 33 No. 4, pp. 1264-1271.



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Copyright © 2014, Emerald Group Publishing Limited

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